1. Field of the Invention
The present invention relates to an inkjet apparatus using an inkjet head ejecting multiple types of inks different in viscosity after evaporation of solvent, and a method for judging replacement timings for components of the apparatus.
2. Description of the Related Art
When ejecting a liquid from a print head, an inkjet apparatus also generates droplets (hereinafter, also called a mist) each smaller than a main droplet. A mist does not adhere only to an ejection surface. While floating in an air current within a printing apparatus, the mist may adhere also to components constituting the printing apparatus such as a mechanism for moving a print medium and an inkjet head relative to each other, a mechanism for performing a recovery operation, and a sensor for performing detection required to perform a printing operation. In other words, the adhesion of ink adversely affects not only the inkjet head but also the components constituting the printing apparatus. As the viscosity increases due to evaporation of ink solvent, the performance of each component, particularly movable components, is reduced, and eventually the performance of the printing apparatus main body cannot be maintained. For this reason, it is necessary to know how much the viscosity of mist adhering to each of these components in the apparatus main body is increased and to make a maintenance such as replacement of the component when it is estimated that the component performance is reduced to such an extent that the performance of the printing apparatus main body cannot be maintained.
To counter such problem, Japanese Patent Laid-Open No. 2005-246697 discloses a configuration which is provided with an ink collecting unit for collecting mist and a fan for generating an air current to suction the mist and lead it toward the collecting unit. Moreover, Japanese Patent Laid-Open No. 2005-246697 discloses a technique in which the amount of ink accumulated in the ink collecting unit as a result of the mist suction is calculated by estimating the amount of mist generated, and, when the amount reaches the maximum ink amount collectable by the ink collecting unit, replacement of the ink collecting unit is prompted.
In an inkjet apparatus, an air current occurs due to ejection of main droplets, and, particularly in a so-called serial printing apparatus, an air current occurs also by the movement of an inkjet head. It should be considered that these air currents also affect the floating state of mist. In other words, not all of the generated mist is necessarily led to the collecting unit by simply generating an air current to suction the mist and lead it toward the collecting unit as in Japanese Patent Laid-Open No. 2005-246697. Accordingly, adhesion of mist on the components constituting the printing apparatus cannot be effectively prevented by this configuration.
Accordingly, it is still necessary to know how much the viscosity of mist adhering to each of the components in the apparatus main body is increased and to make a maintenance such as replacement of the components when it is estimated that the component performance is reduced to such an extent that the performance of the printing apparatus main body cannot be maintained. The technique disclosed in Japanese Patent Laid-Open No. 2005-246697, however, is only for replacement of the collecting unit, and does not consider adhesion of mist on other components in the main body. Moreover, even if the generated mist is effectively led to the collecting unit by the technique disclosed in Japanese Patent Laid-Open No. 2005-246697, the mist may adhere to the suction fan itself in some cases. However, this problem is not recognized in Japanese Patent Laid-Open No. 2005-246697.
As described above, in a situation where an ink of strong tendency to adhere fixedly, particularly an ink which increases in viscosity along with the evaporation of ink solvent, is being used more and more, it is highly desirable to know how much the viscosity of mist adhering to each of the components in the main body is increased and to appropriately know the replacement timing. Moreover, the degree of increase in viscosity along with the evaporation of ink solvent is different depending on the type of ink used in the printing apparatus. Thus, it is highly desirable to appropriately know how much the fixed adhesion is developed and the replacement timing while considering such difference as well.